STUDY ON PRECIPITATION MECHANISM OF ETTRINGITE AS SECONDARY MINERAL

Abstract

In order to clarify the mechanism that monosulfate transforms into ettringite, this study experimentally observed the transformation from monosulfate into ettringite when pure monosulfate phase immersed in the solution containing sulfate ions. The results of this study showed that there was an induction period that the reaction was controlled by dissolution of monosulfate in the early stage when sulfate ion attacked to monosulfate. In addition, after this period, there was an acceleration period that the precipitation rate of ettringite increased with time. Moreover, it was found that the monosulfate kept dissolving even in the acceleration period, and nucleation of ettringite was likely to continue.